Insertion set for a transcutenous sensor with cable connector lock mechanism

ABSTRACT

An improved insertion set is provided for transcutaneous placement of a sensor such as a glucose sensor at a selected site within the body of a patient. The insertion set comprises a mounting base defining an upwardly open channel for receiving and supporting a flexible thin film sensor, in combination with a cap assembled with said mounting base to capture and retain a proximal end of the sensor within said channel. The sensor further includes a distal segment with sensor electrodes thereon which protrudes from the mounting base for transcutaneous placement, wherein the sensor distal segment is slidably carried by a slotted insertion needle fitted through the assembled base and cap. Placement of the insertion set against the patient&#39;s skin causes the insertion needle to pierce the skin to carry the sensor electrodes to the desired subcutaneous site, after which the insertion needle can be slidably withdrawn from the insertion set. The mounting base further includes a fitting and related snap latch members for mated slide-fit releasable coupling of conductive contact pads on a proximal end of the sensor to a cable connector for transmitting sensor signals to a suitable monitoring device.

RELATED APPLICATIONS

This is a division of application Ser. No. 08/871,831 filed on Jun. 9,1997, now U.S. Pat. No. 5,954,643,

BACKGROUND OF THE INVENTION

This invention relates generally to devices and methods for placing asensor at a selected site within the body of a patient. Moreparticularly, this invention relates to an improved and relativelysimple insertion set for quick and easy transcutaneous placement of aflexible thin film sensor of the type used, for example, to obtain bloodglucose readings.

In recent years, a variety of electrochemical sensors have beendeveloped for a range of applications, including medical applicationsfor detecting and/or quantifying specific agents in a patient's bloodand other body fluids. As one example, glucose sensors have beendeveloped for use in obtaining an indication of blood glucose levels ina diabetic patient. Such readings can be especially useful in monitoringand/or adjusting a treatment regimen which typically includes regularadministration of insulin to the patient. In this regard, blood glucosereadings are particularly useful in conjunction with semi-automatedmedication infusion pumps of the external type, as generally describedin U.S. Pat. Nos. 4,562,751; 4,678,408; and 4,685,903; or automatedimplantable medication infusion pumps, as generally described in U.S.Pat. No. 4,573,994.

Relatively small and flexible electrochemical sensors have beendeveloped for subcutaneous placement of sensor electrodes in directcontact with patient blood or other extracellular fluid, wherein suchsensors can be used to obtain periodic readings over an extended periodof time. In one form, flexible transcutaneous sensors are constructed inaccordance with thin film mask techniques wherein an elongated sensorincludes thin film conductive elements encased between flexibleinsulative layers of polyimide sheet or similar material. Such thin filmsensors typically include exposed electrodes at a distal end forsubcutaneous placement in direct contact with patient blood or the like,and exposed conductive contact pads at an externally located proximalend for convenient electrical connection with a suitable monitoringdevice. Such thin film sensors hold significant promise in patientmonitoring applications, but unfortunately have been difficult to placetranscutaneously with the sensor electrodes in direct contact withpatient blood or other body fluid. Improved thin film sensors andrelated insertion sets are described in commonly assigned U.S. Pat. Nos.5,390,671; 5,391,250; 5,482,473; 5,299,571; 5,586,553 and 5,568,806,which are incorporated by reference herein.

Notwithstanding the foregoing improvements in and to thin filmelectrochemical sensors and related transcutaneous insertion sets, thereexists an on-going need for further improvements in such insertion setsparticularly with respect to facilitated and cost efficient manufacture,improvements in quick and easy transcutaneous placement of the thin filmsensor, and simplified attachment of the sensor to a conductive cable orthe like for coupling of sensor signals to the associated monitoringdevice. The present invention fulfills these needs and provides furtherrelated advantages.

SUMMARY OF THE INVENTION

In accordance with the invention, an improved insertion set is providedfor transcutaneously placing a flexible sensor such as a thin filmelectrochemical sensor at a selected site within the body of a patient.The insertion set comprises a mounting base adapted for seated mountingonto the patient's skin, in combination with a cap for assemblytherewith to cooperatively capture and retain the sensor. A distalsegment of the sensor with sensor electrodes thereon is slidably carriedby a slotted hollow insertion needle fitted through the assembledmounting base and cap for piercing the patient's skin to subcutaneouslyplace the sensor electrodes as the mounting base is pressed onto thepatient's skin. The insertion needle can then be slidably withdrawn toleave the sensor electrodes at the desired subcutaneous site. A proximalend of the sensor including conductive contact pads is carried by acable fitting on the mounting base for slide-fit coupling with a cableconnector, with the mounting base and cable connector including snap fitlatch members for releasable interconnection.

In the preferred form, the sensor comprises an elongated thin filmelement with a head at a proximal end thereof including the contact padsseated in a predetermined position and orientation in the cable fittingformed on the mounting base. A proximal segment of the sensor extendsfrom the cable fitting within a recessed channel defined in an uppersurface of the mounting base, with the sensor distal segment protrudingangularly forwardly and downwardly from the mounting base. The cap isdesigned for assembly with the mounting base, as by snap fitinterconnection therewith, to capture and retain the proximal sensorsegment within the recessed channel. In the preferred form, the sensordistal segment and at least a portion of the proximal segment isprotectively carried within a cannula. A proximal portion of the cannulais seated within the channel, and a distal cannular portion extends fromthe mounting base and is slidably carried by the slotted insertionneedle as described in U.S. Pat. No. 5,586,553. The insertion needle isslidably fitted through the assembled mounting base and cap, and isconnected at its upper end to an enlarged hub for facilitatedmanipulation thereof. The hub includes keyed alignment surfaces whichcooperate with associated alignment or guide surfaces on the assembledbase and cap to prevent or minimize needle rotation relative to thesensor and to guide the needle during slide-fit engagement anddisengagement therewith.

The cable fitting formed on the mounting base is sized and shaped forslide-fit coupling with a matingly shaped fitting formed on the cableconnector, for electrically coupling the sensor contact pads withindividual associated conductors of an electrical cable. In thepreferred form, the mounting base includes at least one and preferably aplurality of latch arms for snap fit engagement with latch recessesformed on the cable connector to couple the mounting base and cableconnector together with their respective fittings properly engaged.

In use, the snap fit latch members permit quick and easy connection ofthe insertion set mounting base to the cable connector. The insertionset can then be pressed against the patient's skin so that the insertionneedle pierces the skin and carries the cannula with sensor distalsegment therein to the desired subcutaneous position. The mounting baseis then affixed to the skin, as by suitable adhesive means, and theinsertion needle is withdrawn from the patient leaving the cannula andthe sensor therein at the selected insertion site. When it is necessaryor appropriate to replace with sensor, the used insertion set can besimply removed from the patient to withdraw the sensor from thepatient's skin, followed by detachment of the insertion set from thecable connector for disposal thereof. A replacement insertion set isthen coupled to the cable connector and transcutaneously placed on thepatient as described above.

Other features and advantages of the invention will become more apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a fragmented perspective view illustrating a sensor insertionset embodying the novel features of the invention, wherein the insertionset is depicted in assembled relation with a cable connector;

FIG. 2 is an exploded perspective view of the insertion set;

FIG. 3 is an enlarged and exploded perspective view showing assembly ofthe insertion set components, and depicting an upper side of aninsertion set mounting base;

FIG. 4 is an exploded perspective view showing assembly of the insertionset components, depicting an underside of the mounting base;

FIG. 5 is an underside perspective view of the mounting base shown inFIG. 4, showing a proximal end or head of a flexible thin film sensorseated on the mounting base;

FIG. 6 is another exploded perspective view illustrating assembly of aretainer cap on an upper side of the mounting base;

FIG. 7 is an exploded perspective view similar to FIG. 6, and depictingfurther assembly of the retainer cap with the mounting base;

FIG. 8 is an enlarged perspective view showing the underside of theretainer cap of FIGS. 6 and 7;

FIG. 9 is a perspective view similar to FIGS. 6 and 7, and showing theretainer cap in assembled relation with the mounting base;

FIG. 10 is a perspective view similar to FIG. 9, and depicting aninsertion needle installed on the assembled mounting base and retainercap;

FIG. 11 is an enlarged sectional view taken generally on the line 11—11of FIG. 10;

FIG. 12 is a front end perspective view of the cable connector of FIGS.1 and 2;

FIG. 13 is an exploded perspective view illustrating assembly of thecable connector with the insertion set;

FIG. 14 is a perspective view showing sliding removal of the insertionneedle from the insertion set, following placement of the mounting baseonto the skin of a patient; and

FIG. 15 is a perspective view showing the insertion set and cableconnector mounted onto the skin of a patient, following removal of theinsertion needle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in the exemplary drawings, an improved insertion set referredto generally in FIGS. 1 and 2 by the reference numeral 10 is providedfor placing a biological sensor 12 (FIG. 2) in a selected transcutaneousposition on a patient. The insertion set 10 includes an insertion needle14 for placing a distal end segment of the sensor 12 having sensorelectrodes 15 thereon (FIG. 3) in a selected subcutaneous position indirect contact with patient blood or other body fluid. The insertion setfurther supports the sensor 12 for quick and easy coupling of a proximalend or head 16 having conductive contact pads 18 thereon (FIG. 3) with acable connector 20 (FIG. 1) for coupling sensor signals in turn via anelectrical cable 22 to a suitable monitoring device (not shown).

The insertion set 10 of the present invention is particularly designedfor facilitating quick and easy transcutaneous placement of a flexiblethin film electrochemical sensor of the type used for monitoringspecific blood parameters representative of patient condition. Theinsertion set 10 is designed to place the sensor 12 subcutaneously or atanother selected site within the body of a patient, in a mannerminimizing patient discomfort and trauma. In one preferred application,the sensor 12 may be designed to monitor blood glucose levels, and maybe used in conjunction with automated or semi-automated medicationinfusion pumps of the external or implantable type as described in U.S.Pat. Nos. 4,562,751; 4,678,408; 4,685,903; and 4,573,994, to deliverinsulin to a diabetic patient. However, it will be understood that thesensor may be designed to monitor other patient body fluid parametersfor other applications. Further, is will be understood that the term“patient” can be broadly construed to encompass humans and otheranimals, and that the term “blood” encompasses patient blood and otherextracellular patient fluids.

As shown best in FIGS. 2-4, the flexible thin film sensor 12 comprises arelatively thin and elongated element which can be constructed accordingto so-called thin film mask techniques to include elongated conductiveelements 24 (FIG. 3) embedded or encased between layers of a selectedinsulative sheet material such as polyimide film or sheet. The proximalend or head 16 of the sensor 12 is relatively enlarged and defines theconductive contact pads 18 which are exposed through the insulativesheet material for electrical connection to the cable 22, as will bedescribed in more detail. An opposite or distal end segment of thesensor 12 includes the corresponding plurality of exposed sensorelectrodes 15 for contacting patient body fluid when the sensor distalsegment is placed into the body of the patient. The sensor electrodes 15generate electrical signals representative of patient condition, whereinthese signals are transmitted via the contact pads 18 and the cable 22to an appropriate monitoring device (not shown) for recordation and/ordisplay to monitor patient condition. Further description of flexiblethin film sensors of this general type may be found in U.S. Pat. No.5,391,250, which is incorporated by reference herein.

The sensor 12 is carried by the insertion set 10 which is adapted forplacement onto the skin of a patient (FIGS. 14-15) at the selectedinsertion site. As shown in FIGS. 1-7, the insertion set 10 generallycomprises a compact mounting base 30 having a generally planar or flatunderside surface 32 (FIGS. 4-5) attached to an adhesive patch 34 forpress-on adhesive mounting onto the patient's skin. The mounting base 30is conveniently and economically constructed as a unitary molding oflightweight plastic to include a rear cable fitting 36 for slide-fitcoupling with the cable connector 20. The rear cable fitting 36cooperates with an upwardly open recessed groove or channel 38 formed inan upper surface 40 of the mounting base 30 (FIGS. 2, 3, 6 and 7) toreceive and support the sensor 12.

More particularly, FIGS. 2-5 show the rear cable fitting 36 of themounting base 30 to comprise a rearwardly projecting tubular element 42defining a central bore 44 aligned generally coaxially with a rearwardend of the recessed channel 38. The tubular element 42 includes externalgrooves 46 (FIG. 2) for receiving seal rings 48 adapted for sealedslide-fit engagement with the cable connector 20, as will be described.Importantly, the rearward end of the tubular element 42 terminates in agenerally D-shaped or half-circle fitting key 50 formed as a rearwardextension thereof, and which incorporates a shallow recessed flat orseat 52 formed at the rearward end of the bore 44. This recessed seat 52is sized and shaped to receive and support the proximal head 16 of thesensor 12, with a proximal end of the elongated sensor 12 extending fromsaid head 16 through the bore 44 and lying within the recessed channel38. In the preferred form, the head 16 of the sensor 12 is secured andseated (FIG. 5) within the recessed seat 52 by means of a suitableadhesive or the like. In addition, subsequent to placement of the sensor12 through the bore 44, in the preferred form, the bore 44 ishermetically sealed with a suitable sealant such as curable siliconesealer or the like. For facilitated slide-fit engagement with the cableconnector 20, the seat 52 is formed to ramp angularly rearwardly andupwardly from a central axis of the bore 44, thereby supporting thesensor head 16 with the contact pads 18 presented downwardly andangularly rearwardly.

The recessed channel 38 in the mounting base 30 thus receives andsupports the proximal segment of the thin film sensor 12. As shown inFIGS. 3, 6 and 7, the recessed channel 38 extends forwardly from thefitting bore 44 with a generally horizontal orientation, and then turnsdownwardly and forwardly at an angle of about 45 degrees to extend alongan angled face 53 within a forwardly open gap 54 formed in the front endor nose of the mounting base. A cannula 58 is slidably fitted over atleast a portion of the proximal segment of the sensor 12, to extend alsoover the distal segment to encase and protect the sensor. In thepreferred form, the cannula is constructed from a lightweight plasticmaterial such as a urethane based plastic, and has a double lumenconfiguration as shown in FIG. 11 with the sensor slidably receivedwithin one lumen thereof. The double lumen cannula 58 is especiallysuited for slide-fit engagement with and disengagement from theinsertion needle 14, as will be described in more detail, and includes awindow 59 (FIG. 4) to expose the sensor electrodes 15. The specificcannula construction for receiving and supporting the sensor 12, and forslidably interfitting with the insertion needle 14, is shown anddescribed in more detail in U.S. Pat. No. 5,586,553, which isincorporated by reference herein.

The proximal end of the sensor 12 and the portion of the cannula 58thereon are folded as shown in FIG. 7 to follow the contour of themounting base channel 38, so that the distal segment of the sensor andthe cannula thereon extend and protrude downwardly and forwardly fromthe front of the mounting base 30. The sensor and cannula are capturedand retained in this orientation by a retainer cap 60 shown in FIGS.7-9. This retainer cap 60 is also formed conveniently and economicallyas a lightweight plastic molding and includes means for quick and easysnap fit installation onto the mounting base 30. More specifically, thecap 60 has an elongated and relatively narrow geometry to include a rearhead 62 with a pair of upright keys 64 formed on opposite sides thereoffor vertical slide-fit reception into a mating pair of keyways 66 formedin upright support brackets 68 on the mounting base 30. A front or noseend 70 of the retainer cap 60 is sized and shaped to fit matingly intothe angularly formed gap 54 in the mounting base 30 to retain thecannula 58 and sensor 12 seated in the channel 38 of the ramped face 53.This cap nose 70 includes snap tabs 72 on opposite sides thereof forsnap-fit engagement with snap detents 74 lining the gap 54. When theretainer cap 60 is assembled with the mounting base 30, these componentscooperatively close the top of the channel 38 to capture and retain thesensor and cannula therein. In this regard, the underside of the cap 60desirably includes retainer means such as a plurality of retainer teeth76 (FIG. 8) for frictionally gripping and retaining the cannula with aninterference fit within the channel 38. Alternative means can be used tosecure the cap 60 to the mounting base 30, such as an adhesiveattachment, or ultrasonic bonding means or the like.

The retainer cap 60 further defines a needle port 78 (FIGS. 9 and 10)for pass through reception of the insertion needle 14. The insertionneedle 14 has a hollow and longitudinally slotted configuration (FIG.11) with a pointed or sharpened tip and a rear end anchored to anenlarged hub 80. The hub 80 is manually manipulated to fit the needle 14through the cap port 78, in order to slide the slotted needle intoengagement with the cannula 58 within the forwardly and downwardlyangled portion of the channel 38. In this regard, the needle port 78 issized and shaped to orient the insertion needle 14 for proper angularand rotational alignment with the cannula 58 to insure correct slide-fitengagement therebetween.

More particularly, the hub 80 includes an enlarged tab-like wing 82adapted for easy grasping and handling between the thumb and indexfinger. This enlarged wing 82 projects upwardly from a bifurcated nose84 which is sized and shaped to seat onto the mounting base uppersurface 40, on opposite sides of a raised central section 86 of theretainer cap 60. The hub nose 84 is contoured to defined keyed alignmentor guide surfaces 88 for matingly contacting associated keyed alignmentsurfaces on the mounting base 30, defined by the upper surface 40 and anangularly presented forward face 90 of the support brackets 68. Withthis geometry, the hub 80 is slidably displaced against the mountingbase 30 with the insertion needle 14 extending into and through the capport 78 at the correct angular and rotational orientation for slide-fitengagement with and disengagement from the cannula 58. In the preferredform, the insertion needle 14 slidably assembles with the cannula 58 asdescribed in U.S. Pat. No. 5,586,553 to provide a generally circularcross sectional profile (FIG. 11) protruding from the mounting base.

FIGS. 12 and 13 show the cable connector 20 for coupling with theassembled insertion set 10. As shown, the cable connector 20 comprises acompact coupling element which can also be constructed from lightweightmolded plastic. The cable connector 20 defines a socket fitting 92 formating slide-fit engagement with the rear cable fitting 36 of themounting base 30. This socket fitting 92 has a cylindrical entry portion93 which merges with a generally D-shaped or half-circle step portion 94sized to receive the D-shaped key 50 of the fitting 36. As shown, thesocket fitting 92 includes a plurality of conductive contacts 96 (FIG.12) positioned on the step portion 94 for electrically coupledengagement with the contact pads 18 on the sensor 12, when the insertionset 10 and cable connector 20 are coupled together as viewed in FIG. 13.When assembled, the seal rings 48 sealingly engage the entry portion 93of the socket fitting 92 to provide a sealed connection between thecomponents. Importantly, the D-shaped geometry of the interfittingcomponents 50 and 94 insure one-way interconnection for correctconductive coupling of the cable 22 to the sensor 12.

The insertion set 10 and the cable connector 20 are retained inreleasably coupled relation by interengaging snap fit latch members. Asshown, the mounting base 30 is formed to include a pair of rearwardlyprojecting cantilevered latch arms 97 which terminate at the rearwardends thereof in respective undercut latch tips 98. The latch arms 97 aresufficiently and naturally resilient for movement relative to theremainder of the mounting base 30, to permit the latch arms to besqueezed inwardly toward each other. The permissible range of motionaccommodates snap fit engagement of the latch tips 98 into acorresponding pair of latch recesses 100 formed in the cable connector20 on opposite sides of the socket fitting 92, wherein the latchrecesses 100 are lined with latch keepers 102 for engaging said latchtips 98. The components can be disengaged for uncoupling when desired bymanually squeezing the latch arms 97 inwardly toward each other forrelease from the latch keepers 102, while axially separating themounting base 30 from the cable connector 20.

The insertion set 10 of the present invention is mounted on thepatient's skin quickly and easily to transcutaneously place the sensor12, as viewed in FIGS. 13-15. The insertion set 10 is initially coupledto the cable connector 20 by engaging the snap fit latch members, withthe fitting components 36 and 92 engaged to electrically couple thesensor 12 to the cable 22. The insertion set 10 is then pressed againstthe patient's skin, typically after removing a protective needle guard(not shown) and a release film (also not shown) from the underside ofthe adhesive patch 34 to expose a pressure sensitive adhesive thereon.Pressing the set 10 against the skin causes the insertion needle 14 topierce the skin and thereby carry the cannula 58 with the sensorelectrodes 15 thereon to the desired subcutaneous position. Theinsertion needle 14 is then slidably disengaged from the cannula andsensor by withdrawing the needle from the patient. The insertion set 10can be affixed more securely to the patient, if desired, by anoverdressing (not shown).

When it is necessary or desirable to remove the sensor from the patient,the insertion set is simply removed from the patient's skin to withdrawthe sensor from the subcutaneous site. The insertion set 10 is quicklyand easily disassembled from the cable connector 20 by appropriaterelease of the snap fit latch members. A new insertion set 10 can thenassembled with the cable connector and quickly placed on the patient tosubcutaneously position a new sensor.

A variety of modifications and improvements in and to the transcutaneousinsertion set of the present invention will be apparent to those personsskilled in the art. Accordingly, no limitation on the invention isintended by way of the foregoing description and accompanying drawings,except as set forth in the appended claims.

What is claimed is:
 1. A cable for connecting a sensor set to a monitordevice, wherein the sensor set includes: a mounting base adapted formounting onto a patient's skin, the mounting base including a cablefitting generally at a rear end of the mounting base, wherein the cablefitting of the sensor set includes a tubular element having a centralbore formed therein for pass through reception of a portion of thesensor, and wherein the mounting base further includes lock mechanismfor releasable coupling to the cable; a sensor having at least onesensor electrode thereon, the sensor including at least one contact padconductively coupled to said electrode, the sensor being coupled to themounting base; the cable comprising: a cable with two ends; and a cableconnector connected to one of the two ends of the cable for releasable,interengageable coupling with the lock mechanism on the mounting base ofthe sensor set, wherein the cable connector includes at least one cableconnector contact that is electrically coupled to the at least onecontact pad of the sensor when the mounting base of the sensor set iscoupled to the cable connector, and wherein the tubular element of thesensor set is for mating with a corresponding tubular recess formed inthe cable connector of the cable.
 2. The cable of claim 1, wherein thecable fitting of the sensor set includes a recessed seat for supportingand retaining the sensor head, and wherein the recessed seat fits withinthe a recess in the cable connector.
 3. The cable of claim 1, whereinthe mounting base of the sensor set and the cable connector of the cablehave releasably interengageable snap fit latch members that form thelock mechanism.
 4. The cable of claim 1, wherein the cable fitting ofthe includes a generally D-shaped key formed as a rearward extension ofthe tubular element, the D-shaped key defining a recessed seat forreceiving and supporting the sensor head, and wherein the D-shaped keyis for mating with a corresponding D-shaped key recess formed in thecable connector of the cable.
 5. The cable of claim 4, wherein therecessed seat of the cable fitting is formed at ramp angle relative to acentral axis of the bore, and the cable connector has a correspondingramp formed in the D-shaped key recess of the cable connector.
 6. Thecable of claim 1, wherein the mounting base of the sensor set furtherincludes an upwardly open channel formed therein, and the channelextending from the cable fitting to a front end of the mounting base;wherein the sensor of the sensor set is a flexible sensor having a headformed generally at a proximal end thereof, a proximal segment extendingfrom said head and a distal segment having the at least one sensorelectrode thereon, the head including the at least one contact padconductively coupled to the electrode; and the sensor set furthercomprising: a protective cannula having the sensor distal segment and ata portion of said sensor proximal segment received therein; the sensorproximal segment and a portion of the cannula being seated within thechannel formed in the mounting base, with the sensor distal segment andthe remainder of the cannula protruding from the mounting base; aretainer cap mounted on the mounting base to close the channel and toengage the cannula portion therein to capture and retain the cannulaportion and the sensor proximal segment within the channel; and aninsertion needle extending through the assembled retainer cap andmounting base, the cannula including an engagement structure with theneedle upon insertion of the needle through the assemble retainer capand mounting base, the insertion needle being slidably withdrawable fromthe cannula and from the retainer cap and mounting base.
 7. The cable ofclaim 6, wherein the cable fitting of the sensor set includes a recessedseat for supporting and retaining the sensor head in the sensor set, andwherein the recessed seat fits within the a recess in the cableconnector.
 8. The cable of claim 6, wherein the mounting base of thesensor set and the cable connector of the cable have releasablyinterengageable snap fit latch members that form the lock mechanism. 9.The cable of claim 6, wherein the cable fitting of the includes agenerally D-shaped key formed as a rearward extension of the tubularelement, the D-shaped key defining a recessed seat for receiving andsupporting the sensor head, and wherein the D-shaped key is for matingwith a corresponding D-shaped key recess formed in the cable connectorof the cable.
 10. The cable of claim 9, wherein the recessed seat of thecable fitting is formed at ramp angle relative to a central axis of thebore, and the cable connector has a corresponding ramp formed in theD-shaped key recess of the cable connector.